Rightbase: "Climbing in cloud brings water into the centre tank"
How does that happen? During the climb the air in the centre tank will be venting overboard as it expands due to reducing external atmospheric pressure. How does cloud vapour overcome that, to get into the tank? Even if it could, the volume of tank occupied by the 4000kg or so of fuel used in the climb could not contain enough 'cloud' to hold a signficant amount of water. Also it is very rare to spend more than a few minutes in cloud during the climb, if at all.